Electrode quality evaluation method and electrode manufacturing method

Abstract

Provided is a method of evaluating electrode quality capable of simply and quickly filtering out defective electrodes by measuring a color coordinate value of electrodes before roll-pressing, which specifically includes: providing an electrode which includes a current collector and an active material layer formed on the current collector and has not been roll-pressed; measuring a color coordinate value of the active material layer using an optical instrument; and evaluating the electrode as a good product when the measured color coordinate value satisfies a predetermined electrode quality evaluation criterion and as defective when the measured color coordinate value does not satisfy the predetermined electrode quality evaluation criterion.

The invention claimed is: 
     
       1. A method of evaluating quality of an electrode comprising a current collector and an active material and not being rolled, comprising:
 measuring a color coordinate value of the active material layer using an optical instrument; and 
 evaluating the quality of the electrode as a good product when the color coordinate value satisfies a predetermined electrode quality evaluation criterion and as defective when the color coordinate value does not satisfy the predetermined electrode quality evaluation criterion. 
 
     
     
       2. The method of  claim 1 , wherein the color coordinate value is an L* value, and the predetermined electrode quality evaluation criterion for the L* value is 35.4 or more. 
     
     
       3. The method of  claim 1 , wherein the color coordinate value is an a value, and the predetermined electrode quality evaluation criterion for the a* value is 0.78 or more. 
     
     
       4. The method of  claim 1 , wherein the color coordinate value is a whiteness value, and the predetermined electrode quality evaluation criterion for the whiteness value is 7 or more. 
     
     
       5. The method of  claim 1 , wherein the optical instrument is a spectrophotometer or a colorimeter. 
     
     
       6. The method of  claim 5 , wherein the colorimeter is a contact colorimeter or a non-contact colorimeter. 
     
     
       7. A method of manufacturing an electrode, comprising:
 forming an active material layer by applying a slurry including an active material, a conductive material, and a binder onto a current collector; 
 drying the active material layer to manufacture an electrode which is not roll-pressed; 
 evaluating a quality of the electrode by the method of  claim 1 ; and 
 roll-pressing the electrode which are evaluated as a good product. 
 
     
     
       8. The method of  claim 7 , wherein the slurry is applied in a loading amount of 0.005 g/cm 2  to 0.050 g/cm 2 . 
     
     
       9. The method of  claim 7 , wherein a total heat amount required for the drying satisfies Equation 1:
   Total heat amount required for the drying (kW)=(46.30 −L * value)/0.0077,  Equation 1
 
 wherein, in Equation 1, L* value is a predetermined electrode quality evaluation criterion and is 35.4 or more. 
 
     
     
       10. The method of  claim 7 , wherein a total heat amount required for the drying satisfies Equation 2:
   Total heat amount required for the drying (kW)=(1.09 −a * value)/2.19×10 −5 ,  Equation 2
 
 wherein, in Equation 2, the a value is a predetermined electrode quality evaluation criterion and is 0.78 or more. 
 
     
     
       11. The method of  claim 7 , wherein a total heat amount required for the drying satisfies Equation 3:
   Total heat amount required for the drying (KW)=(13.06−whiteness value)/0.0041,  Equation 3
 
 wherein, in Equation 3, the whiteness value is a predetermined electrode quality evaluation criterion and is 7 or more. 
 
     
     
       12. The method of  claim 7 , wherein the drying is carried out with a total heat amount of 1,000 kW to 1,450 kW. 
     
     
       13. The method of  claim 7 , wherein the active material layer has a thickness of 50 μm to 500 μm.